Maximum sum

#include <bits/stdc++.h>
using namespace std;
#define int long long
 
const int N = 2e5 + 5;
const int MOD = 1e9 + 7;
 
int n, m, k;
int a[N];

signed main() {
    cin.tie(0)->sync_with_stdio(0);
 
    cin >> n;
    for (int i = 1; i <= n; i++) cin >> a[i];

    int ans = *max_element(a + 1, a + n + 1);
    int sum = 0, pre = 0;
    for (int i = 1; i <= n; i++) {
        sum += a[i];
        ans = max(ans, sum - pre);
        pre = min(pre, sum);
    }

    cout << ans << '\n';
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED